Posters belong on a stone surface.
Stories reach us that consumers are using the rollable infrared posters on wooden walls and plaster walls. However, this is not recommended, because such walls absorb the heat from the poster and at some point start to return the heat. This can cause the poster to overheat and cause scorch marks on the wood or plaster wall.
Invroheat only recommends use on a stone wall. Optionally, the poster can also be hung free of any wall, but then the effectiveness will be less great.